In order to investigate the dynamic response of heave plates on the forced vibration of Spar platform of floating wind turbine,based on a model of 5MW floating wind turbine loaded on Umaine-Hywind Spar platform,the paper used numerical simulation method to carry out hydrodynamic calculation for Spar platform of floating wind turbine with different number of vertical plate so as te get frequency-amplitude characteristics of structure movement. The results show that with the increase of vertical plate number, the less the dynamic response of platform becomes, the more the additional mass will increase but the dynamic response does not reduce according to linear relationship attaching more heave plates. However, the reduction of dynamic response didn't show a linear relationship,the effect becomes less evident;under several situations of the same number of heave plates,the effect of space between plates on the whole structure can also not be ignored.